Mastermind

Hide the code and agree the finish

This guide uses Goliath's 2025 The Original Mastermind classic peg edition, product 934423.0, manual 934423.0-10-V02-2412. It has four code positions, six code colors, ten guess rows, 108 large code pegs and 30 small red/white key pegs, with a hinged shield, built-in storage and score tracks. Travel, Junior, Advanced, Code Breakers cards and rotating multiplayer versions need their own instructions.

Bring the complete console, shield, all supplied code and key pegs, one sheet of paper and a pen. Sit at opposite ends of a small stable table with room to reach the rows and see the six colors clearly. Separate large code pegs from small key pegs. Face the shielded end toward the codemaker; establish the codebreaker's left-to-right order and use it throughout.

Choose who sets first. Play two codes, one set by each person; this is the guide's short session within the official equal-role series format. Write both names and start totals at zero. Paper keeps totals clear and can preserve a row if you run short of a peg color. No timer, phone or app is required.

The codemaker raises the shield, secretly fills all four code holes with any combination of the six colors, then conceals the code. A color may appear two, three or four times, and both secret codes and guesses may repeat colors. Leave no code holes empty in the main game. Keep that code unchanged until the round ends.

Count matches without pointing to positions

After a complete four-peg guess, the codemaker compares it with the secret code. First count pegs whose color and position both match: give one small red key peg for each. Then consider only the unmatched pegs on each side. Pair equal colors wherever they occur, once per peg, giving one white key peg per pair. Unmatched leftovers earn nothing. The total can never exceed four key pegs.

For example, let the secret code be red, red, blue, yellow and the guess be red, blue, red, green. The first red is exact. Of the remaining pegs, the guess's blue and second red each match a remaining secret color in another place. Give one red and two white key pegs. If the guess instead is red, green, green, green, give only one red: repeated green guesses cannot earn clues for a color absent from the code.

Place these small pegs in the feedback holes beside that guess in any order. Their positions never tell the solver which large peg was correct. A red clue and a white clue cannot both count the same peg. If a color occurs once in the secret but twice in the guess, it can earn at most one clue, with an exact match taking priority. Small red feedback pegs describe a match of any color; they do not mean a large red code peg was found.

Guess a full row, then read the clues

Keep the evidence reliable

Agree the red-exact, white-misplaced meanings aloud before starting. Older boards and online puzzles may use black instead of red; follow the key colors for this edition. Ask everyone to name the code colors they see in the light. Color discrimination and placing small pegs are part of this physical version; seated play is not a promise that it fits every access need.

The solver can ask the codemaker to recheck the feedback count without seeing the code. If the solver demonstrates incorrect feedback, the official remedy is to replay that code-setting turn: award the codebreaker 3 points, give the codemaker no points for the faulty code, and start a fresh code with the same roles. Then resume the agreed sequence. Do not silently change a past clue after the solver has relied on it.

If a peg supply runs short, use this explicit house aid: write down an earlier row's four colors in order and both clue counts, let both players verify that record, then return that row's pegs to the supply. Keep the written record beside the board and mark its row number. The information, ten-guess limit and scoring stay the same. Do not remove history without recording it or use a differently colored peg without a clear record.

If the shield is accidentally lifted or the hidden code spills, this guide suggests a house remedy: void that unfinished code without points, clear it and make a fresh code with the same roles. For a mistaken verbal explanation, stop and resolve it before another guess. The exact-match counts settle deduction disputes; confidence, memory of another edition or the physical position of a key peg does not.

Quiet conversation is enough. Give the solver space to reason; a guess can test a possibility without being an attempted final solution. After the reveal, compare one useful deduction from the retained rows, then switch roles. You do not need a memorized solving algorithm to begin.

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